1. While still on top of turtle, the rolling reverse omoplata comes into play once you switch the arm to your 'rear' leg. The "hell strangle" is also on the menu. Although you can also get it with the arm in the up position, I find it's a more cruel choke with the arm down. See below for the "hell strangle-arm up" variation:

Bottom line is, for me, there are more submission options as opposed to trapped guy's arm being in the up configuration.

2. I personally have more success finishing crucifixes when the arm is pointing down. It seems to help when I turn away to finish the submission. I know that when I do escape from the crucifix position, it happens more often when my arm is up.

One note about finishing crucifixes. Once you turn onto your side, the person being crucifixed shoulders need to be close to, or outright touching the ground in order to finish the move with the least amount of effort.

I know this because when I am put in the position I always try to drive my shoulders up off the ground and across their body while they are still on their back. This prevents them from getting on their side so that they might then turn away and finish me. Conversely, the closer my shoulders are to the mat, the fewer my defensive options.

I like that second one, haven't see it before. It's a safer choke than trying to transition to the RNC which is where I frequently lose control and end up losing the crucifix. I'ma work that one into my game.